Multi-layer polypropylene (MLPP) insulation coating is used for thermal insulation of subsea pipelines. However in recent years - with higher wellhead operating temperatures - high temperature (HT) Fusion Bonded Epoxies have been used. This paper describes the author's experience with the MLPP systems over the last 20 years.
Subsea flowlines and risers experience fatigue cycles due to thermal and/or pressure transients or vortex induced vibration (VIV). Tests were performed under constant stress intensity factor (K) levels, in a mildly sour environment and in seawater under cathodic protection to understand the difference in the CRG.